1. Field of the Invention
The present invention generally relates to testing of greensheets, and more particularly to an improved structure and test method that forms non-functional wires in kerf regions that can be tested in place of the functional wires in the greensheet.
2. Description of the Related Art
Conventionally, electrical measurements are used to determine the proper design and manufacturing of ceramic module wiring. These measurements occur near the end of the manufacturing process. Thus, design and/or manufacturing errors and defects are conventionally not found until late in the process. The invention described below provides a method and structure to measure the “as manufactured” line widths and spacings before or after package sectioning.
Circuit traces, or nets, in a multilayer ceramic substrate suffer increasing demand from circuit designers, application requirements and cost. Line widths and spacings are being made smaller and, in addition, net electrical requirements are getting tighter (i.e., lower resistance, electrical characteristic impedance, etc.). The typical process flow for manufacturing a multi-layer ceramic module (MLC) does have optical inspections after screening the circuit trace/net onto the layer, however this optical inspection tool only examines portions of the circuitry and can only measure the shape of the net, not the performance of the net.
Electrical testing of the net can occur only at the end of the manufacturing process and errors detected at the end of the manufacturing process result in scrap of the module since repair is not possible. This invention described below provides a methodology/structure where rapid analysis can be performed to identify the layer(s) with incorrect linewidths, line cross section, composition and/or spacings.